1. Field of Invention
The present invention resides in the field of materials handling technology and relates to an apparatus for aligning a sheet product conveyed on a conveying surface of a conveyor system, according to the preamble to claim 1. The invention further relates to a method for aligning the sheet product through the use of said apparatus, as claimed in claim 14.
2. Description of Related Art
Conveyor systems for sheet products, such as, for example, printed matter, are known to the person skilled in the art. The products are here conveyed on a conveyor system and are aligned by means of guide plates and/or stop cams. Specifically in the conveyance of printed matter, whole stacks of sheet products are often conveyed.
In this context, CH-A-699 597, for instance, discloses a conveying apparatus for conveying and aligning sheet products or stacks of sheet products. The products can be aligned at their trailing edge by means of sliding cams and at their leading edge by means of cams which run ahead of the sliding cams. With this apparatus it is possible to align sheet products or a stack of sheet products along an edge running at right angles to the direction of conveyance.
GB-A-921 679 discloses an apparatus for aligning sheet products which are transported by means of a conveyor belt defining a conveying surface. Furthermore, an alignment conveyor belt is arranged so as to bear directly against the conveying surface of the conveyor belt.
The direction of conveyance of the alignment conveyor belt runs at an acute angle to the direction of conveyance of the conveyor belt. The alignment conveyor belt takes up an article conveyed by the conveyor belt, which is then laterally displaced by the alignment conveyor belt with respect to the direction of conveyance of the conveyor belt and is brought to bear with a side edge against the alignment surface and is then aligned. Owing to the narrow gap between the alignment conveyor belt and the conveyor belt, the apparatus according to GB A-921 679 is geared to aligning only single articles. By contrast, no provision is made for conveying stacks of products.
Particularly in the case of printed matter, moreover, it is often wished to align only the topmost product of a product stack. In known alignment systems, the problem often exists that, because of the comparatively large force acting upon the topmost sheet product, the bottom products of the product stack are displaced due to friction. The adjustment of the force then proves difficult, particularly when, as described in GB-A-921 679, rollers are used to align the products.